full pen weld on 3/16 al

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i am trying to get a nice full penetration weld on 3/16 6061 plate.  seems to be either to much weld on the backside or there is a line where the joint meets.  i know how to tig pretty well, just never had to have my full pen welds look perfect.  please help me with what i am dong wrong.
Reply:Originally Posted by threedi am trying to get a nice full penetration weld on 3/16 6061 plate.  seems to be either to much weld on the backside or there is a line where the joint meets.  i know how to tig pretty well, just never had to have my full pen welds look perfect.  please help me with what i am dong wrong.
Reply:more info.. need more   machine settingsfiller diam.  oh and yes sir ,pics wood be niceidealarc 250/250 ac-dc tigidealarc 250/250 ac-dc tig #2 used for sticklincoln sp100hh125dual arbor grinder polisher30 yrs of hand tools52 pitch blocks 6p-26prake gauge -pitch gaugeG&D prop repair 918-207-6938Hulbert,okla 74441
Reply:Hello threed, unlike the majority of other materials, you won't have the same type of penetration and look to the penetration as you might with just about any other material.      Consider this: aluminum relies upon the protection from the atmosphere by using an inert gas, either argon,helium, or a combination of the two. Additionally, you have the benefit of the alternating current to assist with the cleaning of the surface oxides. This is why the finished weld bead of a properly executed aluminum weld is so shiny. The backside of a full-pen aluminum weld will not look the same mainly due to the lack of cleaning action of the arc. You will always have some form of lines, or other less aesthetic appearance due to the surface oxides that can't be cleaned as a result of being blocked from arc action by being on the opposite side. Purges may help a bit with excessive oxidation, but will not completely provide the sort of benefit that is realized on say stainless or carbon steel that has been provided with an argon purge. A bit for you to think about. Even with this said, I'll echo what others have said, pictures would certainly help with other possible issues. Best regards, AllanLast edited by aevald; 02-17-2011 at 12:04 AM.aevald
Reply:Aevald, Actually on an O/F weld, it is sometimes impossible to distinguish the front and back of the weld as the flux is on both and 100% penetration is quite easy. Thats really the electric welding drawback and advantage......not using a flux
Reply:Hello makoman1860, definitely understand your point, I'm thinking GTAW and not oxy/fuel. Best regards, Allanaevald
Reply:i'll post some pictures tomorrow.  i am using a watercooled dynasty 350.  i usually set the machine at 350amps & just use the pedal.  i usually run it in advanced square wave and anywhere from 250 to 400hz.  i really love this welder!!!
Reply:Originally Posted by makoman1860Aevald, Actually on an O/F weld, it is sometimes impossible to distinguish the front and back of the weld as the flux is on both and 100% penetration is quite easy. Thats really the electric welding drawback and advantage......not using a flux
Reply:Originally Posted by DiabolicZCan you use flux on the back side of a GTAW weld? I was watching a vid the other day of a guy who welded some thin aluminum together using oxy and flux. He then proceeded to beat the weld with a hammer repeatedly on both sides. Basically, just a really strong weld and I was very impressed. Can you get 100% penetration like that with a TIG and flux is all I'm wondering?
Reply:Originally Posted by makoman1860Ehhhhhhh technicly yes, however its not a practical venture. The flux has to be oven dried and a specific composition. Not soething easily available.  You can get a lot of melt through with tig, but there is always a surface oxide "line", and that is normally where the fatigue crack starts.
Reply:Originally Posted by makoman1860Ehhhhhhh technicly yes, however its not a practical venture. The flux has to be oven dried and a specific composition. Not soething easily available. The only other way I have seen equivelant welds done via tig was to clean and weld them in a purge tent. You can get a lot of melt through with tig, but there is always a surface oxide "line", and that is normally where the fatigue crack starts. Some alloys are better than others for resisting this to a degree.
Reply:threed - I would set up the 3/16" aluminum plates with a little gap in between them to fill, to help improve the penetration.  Perhaps stick a small MIG wire (.030"-.0.35"'ish) in between the plates before tackwelding to set up a narrow gap.  Alternately, chamfer or bevel the top edges of the plates, leaving a v-shaped groove to fill.  This is assuming you are talking about a butt weld joint.  If you are welding a corner joint, make it an "open corner" (where the two edges are butted up against each other)Then when you are welding, look for a "keyhole" melt-through like pattern you will repeatedly fill with your filler rod as you progress your weld bead along the joint.  This will ensure you are penetrating all the way through to the backside.This kind of joint prep is important on 6061, because without adequate filler rod dilution you can get "hot cracking" (which will look like a hairline crack right through the weld bead immediately upon puddle solidification.)Also, if you can place a copper back-up plate behind the weld seam, it will help to ensure the material doesn't sag through if you use a little too much heat.  Experiment on some test coupons to obtain the proper technique and settings (current level, torch angle, travel speed, AC frequency and balance %, etc) until you get satisfactory results before welding your actual project's pieces.Alternatively, if you have access to the backside, just perform a second weld operation on the second side after welding up the first side.Last edited by jakeru; 02-20-2011 at 09:55 PM.
Reply:Originally Posted by DiabolicZOk, so let me ask you this... Would it be beneficial to put flux on the back side of an AL TIG weld just for precautions sake, just to POSSIBLY get a better weld? Or would you do more harm than good?
Reply:Typically when you weld aluminum with tig the parent metal gets harder and is reluctant to be worked or formed......OA welding with strips cut from the material being welded lend itself to be formed since it stays soft and in an annealed state...You will see body panels get welded this way so they can be worked and formed easier without cracking  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:Originally Posted by threedi am trying to get a nice full penetration weld on 3/16 6061 plate.  seems to be either to much weld on the backside or there is a line where the joint meets.  i know how to tig pretty well, just never had to have my full pen welds look perfect.  please help me with what i am dong wrong.
Reply:sorry i have not got pics yet.  the problem that i am having is "hot cracking" as jakeru stated.  guess i need to let off the pedal a bit cause my "keyhole" is a bit big.
Reply:Don't be afraid to push that filler in when running higher amp settings......You don't want to lose the puddle because then your using parent metal  (Undercut)  Miller Dynasty 350Twenty Six HammersThree Crow BarsBig Rock
Reply:What wire you using? 4043 or 5356?